A guy called
"Oil man" from Opie tends to post this quite a bit:
I'm afraid picking a good oil is difficult due to the labelling of synthetics.
The Mobil vs Castrol court gas in the US changed things forever I'm afraid.
I hope this will go some way to explaining why it's a minefield out there and you must be very careful!
Costs of synthetics vary considerably.
The most expensive are the
Ester types originally only used in jet engines.
These cost 6 to 10 times more than high quality mineral oils.
The cheapest synthetics are not really synthetic at all, from a chemists point of view.
These are in fact specially refined light viscosity mineral oils known as
hydrocracked.
These have some advantages over equivalent mineral oils, particularly in lower viscosity motor oils such as 5w-30 or other oils with a low
W rating such as 5w-50 etc and they cost about 1.5 times more than good quality mineral fractions.
We use several different grades of this base oil, where appropriate.
This is the
synthetic which is always used in cheap oils that are labelled
synthetic.
Yes its a cruel world, you get what you pay for!
Now, you may ask, why are these special mineral oils called
synthetic? Well, it was all sorted in a legal battle that took place in the USA about ten years ago.
Sound reasons
(including evidence from a Nobel Prize winning chemist) were disregarded and the final ruling was that certain mineral bases that had undergone extra chemical treatments could be called
synthetic.
The marketing executives wet their knickers with pure delight! They realised that this meant, and still does, that the critical buzz-word
synthetic could be printed on a can of cheap oil provided that the contents included a few percent of
hydrocracked mineral oil, at a cost of quite literally a few pence.
So, the chemistry of
synthetics is complex and so is the politics!
The economics are very simple.
If you like the look of a smart well-marketed can with
synthetic printed on it, fair enough, it will not cost you a lot; and now you know why this is the case.
But, if you drive a high performance car, and you intend to keep it for several years, and maybe do the odd
track day, then you need a genuine Ester/PAO
(Poly Alpha Olefin) synthetic oil, this oil costs more money to buy, because it costs us a lot of money to make, very simply, you always get what you pay for!
This article was written by John Rowland
(Chief R&D Chemist of Silkolene/Fuchs) and I have his permission to publish it as his view is that people should be informed before they buy.
There are some products however that are PAO or PAO/Ester blends out there.
For example, all 0w oils will have a PAO content as to meet the 0w test
(-35 degC) and the sae number 30,40 etc it has to be as a mineral oil cannot achieve these wide ranges.
The same goes for most 5w-40's, they may not be fully synthetic in the true sense of the word but they will contain a percentage of the good stuff
(the higher the better).
10w's and 15w's etc, almost all are hydrocracked as mineral oils can manage the
"w" temps much easier on their own.
So what should you look out for, well, there are the totally overpriced Redline, Royal Purple etc which are US oils or a little closer to home you have the following oils
Silkolene PRO S 5w-40 and 10w-50
(Ester/PAO)
Mobil 1
(PAO)
Fuchs Titan Supersyn Range
(PAO)
Motul 300V
(PAO/Ester)
Most others ignore unless the Oil company will tell you what's in them
(and in most cases they won't) and.
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Don't be misled by the statement
"its synthetic sir" ask what type of synthetic!
You will find some good technical data here:
http://www.opieoils.co.uk/lubricants.htm
Why are esters so good?
Due to their structure, ester molecules are
polar; they stick to metal surfaces using electrostatic forces.
This means that a protective layer is there at all times, even during that crucial start-up period.
This helps to protect cams, gears, piston rings and valve train components, where lubrication is
boundary rather than
hydrodynamic, i.e.
a very thin non-pressure fed film has to hold the surface apart.
Even crank bearings benefit at starts, stops or when extreme shock loads upset the
hydrodynamic film.
DO SYNTHETICS REQUIRE A 3000 MILE OIL CHANGE?
The necessity of 3,000 mile oil changes is a myth that has been handed down for decades.
Well its good for the oil companies as they sell more oil!
Synthetic oils are much better value for money than petroleum oils, you just have to know how to use them to your benefit.
If you're one who thinks that synthetics are just a marketing ploy to make more money off the same bottle of oil, read through this and judge for yourself.
The whole point of using a synthetic oil is peace of mind, knowing that you can trust the oil in your car to protect the engine.
There are only a few basic reasons why it is necessary to change your oil, and they all, in the end, have to do with decreased protection of your engine and decreased performance.
If these elements can be minimized, then there will be little or no reason to change the oil.
What causes the oil to breakdown?
Firstly, all oil breaks down.
That generally will include basestocks and additives
(actually additives are really
"used up" rather than broken down.
The most significant difference from one oil to another is how quickly breakdown occurs.
Although there are many factors that contribute to the breakdown of an oil, temperature is one of the most important.
Petroleum oil begins to break-down almost immediately.
A high quality synthetic, on the other hand, can last for many thousands of miles without any significant reduction in performance or protection characteristics.
Synthetics designed from the right combination of basestocks and additives can last indefinitely with the right filtration system.
The first major difference between petroleum and synthetic oil is heat tolerance.
Flash point is a technical specification referenced by most oil manufacturers which is an indicator of heat tolerance.
The lower the flash point of an oil the greater tendency for that oil to suffer vaporization loss at high temperatures and to burn off on hot cylinder walls and pistons.
This leads to oil thickening and deposit build-up on critical engine components.
So, the higher the flash point the better.
200 degrees C, is the absolute MINIMUM to prevent possible high consumption and oil thickening due to burn-off.
Today's engines are expected to put out more power from a smaller size and with less oil than engines of the past.
Therefore, the engines run much hotter than they used to.
That puts an increased burden on the oil.
Synthetics are up to the task.
Although synthetics are MUCH less prone to burn-off than are petroleum oils, there is still a small amount of burn-off during extremely high temperature operation.
The manner in which petroleum and synthetic oils burn off is important.
As a refined product, petroleum oil molecules are of varying sizes.
So, as a petroleum oil heats up, the smaller molecules begin to burn off.
Deposits and sludge are left behind to coat the inside of your engine.
In addition, as smaller particles burn off, the larger, heavier molecules are all that is left to protect the engine.
Unfortunately, these larger particles do not flow nearly as well and tend to blanket the components of your engine which only exacerbates the heat problem as friction builds-up.
Synthetic oils, on the other hand, because they are not purified, but rather designed within a lab for lubrication purposes, are comprised of molecules of uniform size and shape.
Even if a synthetic oil does burn a little, the remaining oil has the same chemical characteristics that it had before the burn off.
There are no smaller molecules to burn-off and no heavier molecules to leave behind.
Synthetics contain far fewer contaminants than petroleum oils since they are not a refined product.
As a result, if oil burn-off does occur, there are few, if any, contaminants left behind to leave sludge and deposits on engine surfaces.
Obviously, this leads to a cleaner burning, more fuel efficient engine.
It is also important to note that synthetics do a much better job of
"cooling" engine components during operation.
Because of their unique flow characteristics, engine components are likely to run 10 to 30 degrees cooler than with petroleum oils.
This is important, because the hotter the components in your engine get, the more quickly they break down.
Additive depletion comes into play when discussing oil drain intervals.
If additives are depleted, the oil cannot effectively do it's job.
So, the oil must be changed.
It is true that the additives in many oils begin breaking down after only a few thousand miles.
What needs to be recognized is that there are different quality
"grades" of additives just as there are different quality grades of just about any other product that you buy.
Many oil companies are using the same additives in their oils as all of the other companies because they are cheap.
That's why the oil costs less.
You get what you pay for!
If they were willing to spend the money on top-quality additive packages for their oils, every synthetic on the market would be recommended for extended drain intervals, and they would all be more expensive.
The technology has been around for years.
The problem is that oil companies make more money selling a cheaper grade oil and making sure that you change it more often.
What do the oil additives in your oil do?
Viscosity Retention
Additives are used to maintain a stable viscosity over a wide temperature range.
Synthetics need less of these additives than petroleum oils do because synthetic basestocks maintain a fairly stable viscosity by themselves.
Also, the additives that are used are more stable than those used in petroleum oils.
As a result, petroleum oils must be changed often because they quickly become unable to retain the viscosity levels necessary to protect your engine
(their high temperature viscosity drops off).
Synthetic oils don't really have that problem because both the basestocks and the additives are more stable.
Additives are also used to keep oil contamination in check and to keep it from damaging your engine.
These additives keep potentially wear causing contaminants suspended and contained in your oil so they don't cause excessive wear or deposit build-up within your engine before your filter can remove them.
Synthetics generally have higher additive treat rates than petroleum oils
(in addition to using higher quality, more expensive additives), so they can perform this contaminant control function for a much longer period of time than a petroleum oil can.
